Method for forming a metal structure

Abstract

A semiconductor wafer comprises a plurality of die areas, at least a first scribe line area and at least a second scribe line area surrounding each die area, at least a first metal structure positioned in the first scribe line area, and at least a second metal structure positioned in the second scribe line area. The first metal structure comprises at least a first slot split parallel to the first scribe line area, or comprises a plurality of openings arranged in an array. The second metal structure comprises at least a second slot split parallel to the second scribe line area, or comprises a plurality of openings arranged in an array.

1. A method for forming a metal structure comprising:
 providing a semiconductor wafer that defines a scribe line area, and the scribe line area comprising at least a first low-k dielectric layer; 
 forming at least a first metal piece in the first low-k dielectric layer in the scribe line area, and the first metal piece comprising at least a slot split within the first metal piece parallel to the scribe line area; 
 forming a second low-k dielectric layer in the scribe line area, and the second low-k dielectric layer comprising a plurality of slot via holes to expose portions of the first metal piece; and 
 forming at least a second metal piece on a surface of the second low-k dielectric layer and a plurality of via strips filling up the slot via holes, and the second metal piece being electrically connected to the first metal piece by the via strips. 
 
   
   
     2. The method of  claim 1 , wherein the first metal piece comprises a test key, a test component of feature dimension, an alignment mark, or a WAT pad. 
   
   
     3. The method of  claim 1 , wherein the semiconductor wafer further comprises at least two die areas, and the scribe line area is formed between the die areas. 
   
   
     4. The method of  claim 1 , wherein the first and the second low-k dielectric layer comprise fluorinated silicate glass (FSG), phosphosilicate glass (PSG), undoped silicate glass (USG), hydrogen silsequoxiane (HSQ), or methyl silsequoxiane (MSQ). 
   
   
     5. The method of  claim 1 , wherein the via strips are positioned between the first metal piece and the second metal piece to electrically connect the first metal piece and the second metal piece. 
   
   
     6. The method of  claim 1 , wherein the metal structure comprises titanium, tantalum, tungsten, aluminum, copper, titanium nitride, tantalum nitride, or an alloy thereof. 
   
   
     7. The method of  claim 1 , further comprising a step of forming a passivation layer after the step of forming the second metal piece and the via strips, and the passivation layer exposing portions of the second metal piece. 
   
   
     8. The method of  claim 1 , wherein in the step of forming the first metal piece, the first metal piece comprises a plurality of marginal slots extending inward from edges of the first metal piece. 
   
   
     9. The method of  claim 8 , wherein in the step of forming the first metal piece, the first metal piece further comprises a plurality of staggered slots, and the marginal slots and the staggered slots are arranged alternately. 
   
   
     10. The method of  claim 9 , wherein in the step of forming the second metal piece and the via strips, each via strip is in a shape of sawtooth, wave or rectangular waveform.